From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 15 Jul 2013 07:14:36 +0000 (+0300)
Subject: math: improve how casts are handled
X-Git-Tag: 1.60~545
X-Git-Url: https://repo.or.cz/w/smatch.git/commitdiff_plain/840f2b035fe0a3392853ba3e24ea85caf7ee3bb5

math: improve how casts are handled

This is for code like:

	int x = le16_to_cpu(foo);

It is useful to know that x is a number between 0 and u16max, as opposed to
being a negative number or something.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---

diff --git a/smatch_math.c b/smatch_math.c
index a6cbc2b2..3ba47bff 100644
--- a/smatch_math.c
+++ b/smatch_math.c
@@ -715,6 +715,23 @@ static struct range_list *handle_call_rl(struct expression *expr, int implied)
 	return db_return_vals(expr);
 }
 
+static struct range_list *handle_cast(struct expression *expr, int implied)
+{
+	struct range_list *rl;
+	struct symbol *type;
+
+	type = get_type(expr);
+	rl = _get_rl(expr->cast_expression, implied);
+	if (rl)
+		return cast_rl(type, rl);
+	if (implied == RL_ABSOLUTE)
+		return alloc_whole_rl(type);
+	if (implied == RL_IMPLIED && type &&
+	    type->bit_size > 0 && type->bit_size < 32)
+		return alloc_whole_rl(type);
+	return NULL;
+}
+
 static struct range_list *_get_rl(struct expression *expr, int implied)
 {
 	struct range_list *rl;
@@ -740,8 +757,7 @@ static struct range_list *_get_rl(struct expression *expr, int implied)
 	case EXPR_CAST:
 	case EXPR_FORCE_CAST:
 	case EXPR_IMPLIED_CAST:
-		rl = _get_rl(expr->cast_expression, implied);
-		rl = cast_rl(type, rl);
+		rl = handle_cast(expr, implied);
 		break;
 	case EXPR_BINOP:
 		rl = handle_binop_rl(expr, implied);